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Pathology – Tuberculosis
Pathogen
• Mycobacterium tuberculosis, an acid-fast bacillus with a rod form. Epidemiology • The most prevalent infectious disease globally. • Causes the demise of 2 million individuals annually.
Transmission
• Respiratory transmission from an infectious individual with active pulmonary tuberculosis (TB).
Immunopathogenesis
• Inhaled bacilli are phagocytosed by alveolar macrophages, however they can persist and proliferate within these cells. Mycobacteria disseminate within macrophages in the bloodstream to oxygenated regions of the body, including the lung apices, kidneys, bones, and meninges. • Subsequent to many weeks, mycobacteria-specific CD4+ helper T-cells are activated upon MHC class II antigen presentation by macrophages. • Th1 subset helper T-cells generate IFN-γ, which activates macrophages into epithelioid macrophages that aggregate into granulomas, isolating the mycobacteria in an anoxic and acidic milieu.
• The majority of immunocompetent hosts retain the infection, resulting in scarring.
Active disease typically manifests in the elderly, malnourished, diabetic, immunosuppressed, or alcoholic individuals. Active disease may manifest as pulmonary (75%) or extrapulmonary (25%).
Presentation
• Pulmonary tuberculosis manifests as a chronic pneumonia characterized by a persistent cough, fever, night sweats, weight loss, and anorexia.
• Extrapulmonary tuberculosis may appear with meningitis, lymphadenopathy, genitourinary symptoms, or discomfort in bones or joints
.Diagnosis • Acid-fast bacilli may be detected in sputum, pleural fluid, or bronchoalveolar lavage (BAL) fluid. • Culture is the definitive inquiry, although it may require up to 12 weeks for results. Polymerase chain reaction (PCR) is applicable for the diagnosis and identification of drug-resistant strains.
Histopathology
The histopathological characteristic is necrotizing granulomatous inflammation.
Prognosis: • Following antituberculous therapy, the majority of individuals achieve complete recovery. • If left untreated, approximately fifty percent of individuals will ultimately succumb to the virus.
• Prognosis is poorer in the presence of concurrent HIV or organisms exhibiting multidrug resistance.
Pathogen
• Mycobacterium tuberculosis, an acid-fast bacillus with a rod form. Epidemiology • The most prevalent infectious disease globally. • Causes the demise of 2 million individuals annually.
Transmission
• Respiratory transmission from an infectious individual with active pulmonary tuberculosis (TB).
Immunopathogenesis
• Inhaled bacilli are phagocytosed by alveolar macrophages, however they can persist and proliferate within these cells. Mycobacteria disseminate within macrophages in the bloodstream to oxygenated regions of the body, including the lung apices, kidneys, bones, and meninges. • Subsequent to many weeks, mycobacteria-specific CD4+ helper T-cells are activated upon MHC class II antigen presentation by macrophages. • Th1 subset helper T-cells generate IFN-γ, which activates macrophages into epithelioid macrophages that aggregate into granulomas, isolating the mycobacteria in an anoxic and acidic milieu.
• The majority of immunocompetent hosts retain the infection, resulting in scarring.
Active disease typically manifests in the elderly, malnourished, diabetic, immunosuppressed, or alcoholic individuals. Active disease may manifest as pulmonary (75%) or extrapulmonary (25%).
Presentation
• Pulmonary tuberculosis manifests as a chronic pneumonia characterized by a persistent cough, fever, night sweats, weight loss, and anorexia.
• Extrapulmonary tuberculosis may appear with meningitis, lymphadenopathy, genitourinary symptoms, or discomfort in bones or joints
.Diagnosis • Acid-fast bacilli may be detected in sputum, pleural fluid, or bronchoalveolar lavage (BAL) fluid. • Culture is the definitive inquiry, although it may require up to 12 weeks for results. Polymerase chain reaction (PCR) is applicable for the diagnosis and identification of drug-resistant strains.
Histopathology
The histopathological characteristic is necrotizing granulomatous inflammation.
Prognosis: • Following antituberculous therapy, the majority of individuals achieve complete recovery. • If left untreated, approximately fifty percent of individuals will ultimately succumb to the virus.
• Prognosis is poorer in the presence of concurrent HIV or organisms exhibiting multidrug resistance.
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